Two identical closely spaced circular disks form a parallel-plate capacitor. Transferring 2.7×10° electrons from one disk to the other causes the electric field strength between them to be 1.0x105 N/C. Part A What are the diameters of the disks? Express your answer with the appropriate units. HẢ ? D= Value m

Two identical closely spaced circular disks form a parallel-plate capacitor. Transferring 2.7×10° electrons from one disk to the other causes the electric field strength between them to be 1.0x105 N/C. Part A What are the diameters of the disks? Express your answer with the appropriate units. HẢ ? D= Value m

University Physics Volume 2

18th Edition

ISBN:9781938168161

Author:OpenStax

Publisher:OpenStax

Chapter7: Electric Potential

Section: Chapter Questions

Problem 70P: A simple and common technique for accelerating electrons is shown in Figure 7.46, where there is a...

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Lightning can be studied with a Van de Graaff generator, which consists of a spherical dome on which charge is continuously deposited by a moving belt. Charge can be added until the electric field at the surface of the dome becomes equal to the dielectric strength of air. Any more charge leaks off in sparks as shown in Figure P25.52. Assume the dome has a diameter of 30.0 cm and is surrounded by dry air with a "breakdown" electric field of 3.00 106 V/m. (a) What is the maximum potential of the dome? (b) What is the maximum charge on the dome?
Three charged particles are arranged on corners of a square as shown in Figure OQ23.11, with charge Q on both the particle at the upper left corner and the particle at the lower right corner and with charge +2Q on the particle at the lower left corner. (i) What is the direction of the electric field at the upper right corner, which is a point in empty space? (a) It is upward and to the right. (b) It is straight to the right. (c) It is straight downward. (d) It is downward and to the left. (e) It is perpendicular to the plane of the picture and outward. (ii) Suppose the +2Q charge at the lower left corner is removed. Then does the magnitude of the field at the upper right corner (a) become larger, (b) become smaller, (c) stay the same, or (d) change unpredictably?
A free electron and a free proton are released in identical electric field. (i) How do the magnitudes of the electric force exerted on the two particles compare? (a) It is millions of times greater for the electron. (b) It is thousands of times greater for the electron. (c) They are equal. (d) It is thousands of times smaller for the electron. (e) It is millions of times smaller for the electron. (ii) Compare the magnitudes of their accelerations. Choose from the same possibilities as in part (i).
Two solid spheres, both of radius 5 cm. carry identical total charges of 2 C. Sphere A is a good conductor. Sphere B is an insulator, and its charge is distributed uniformly throughout its volume, (i) How do the magnitudes of the electric fields they separately create at a radial distance of 6 cm compare? (a) EA EB= 0 (b) EA EB 0 (c) EA = EB 0 (d) 0EAEB (e) 0 = Ea EB (ii) How do the magnitudes of the electric fields they separately create at radius 4 cm compare? choose from the same possibilities as in part (i).
A simple and common technique for accelerating electrons is shown in Figure 18.55, where there is a uniform electric field between two plates. Electrons are released, usually from a hot filament, near the negative plate, and there is a small hole in the positive plate that allows the electrons to continue moving. (a) Calculate the acceleration of the electorn if the field strength is 2.50104 N/C. (b) Explain why the electron will not be pulled back to the positive plate once it moves through the hole.
Earth has a net charge that produces an electric field of approximately 150 N/C downward at its surface. (a) What is the magnitude and sign of the excess charge, noting the electric field of a conducting sphere is equivalent to a point charge at its center? (b) What acceleration will the field produce on a free electron near Earth’s surface? (c) What mass object with a single extra electron will have its weight supported by this field?
(a) What is the direction and magnitude of an electric field that supports the weight of a free electron near the surface of Earth? (b) Discuss what the small value for this field implies regarding the relative strength of the gravitational and electrostatic forces.
A simple and common technique for accelerating electrons is shown in Figure 7.46, where there is a uniform electric field between two plates. Electrons are released, usually from a hot filament, near the negative plate, and there is a small hole in the positive plate that allows the electrons to continue moving, (a) Calculate the acceleration of the electron if the field strength is 2.50104 N/C . (b) Explain why the electron will not be pulled back to the positive plate once it moves through the hole. Figure 7.46 Parallel conducting plates with opposite charges on them create a relatively uniform electric field used to accelerate electrons to the right. Those that go through the hole can be used to make a TV or computer screen glow or to produce X- rays.
(a) Would life be different if the electron were positively charged and the proton were negatively charged? (b) Does the choice of signs have any bearing on physical and chemical interactions? Explain your answers.
Problems 72, 73, and 74 are grouped. 72. A Figure P26.72 shows a source consisting of two identical parallel disks of radius R. The x axis runs through the center of each disk. Each disk carries an excess charge uniformly distributed on its surface. The disk on the left has a total positive charge Q, and the disk on the right has a total negative charge Q. The distance between the disks is 3R, and point A is 2R from the positively charged disk. Find an expression for the electric potential at point A between the disks on the x axis. Approximate any square roots to three significant figures. FIGURE P26.72 Problems 72, 73, and 74.
A thin, square, conducting plate 50.0 cm on a side lies in the xy plane. A total charge of 4.00 108 C is placed on the plate. Find (a) the charge density on each face of the plate, (b) the electric field just above the plate, and (c) the electric field just below the plate. You may assume the charge density is uniform.
(a) Find the electric field at x = 5.00 cm in Figure 18.52 (a), given that q = 1.00 C. (b) at what position between 3.00 and 8.00 cm is the total electric field the same as that for ? 2q alone? (c) Can the electric field be zero anywhere between 0.00 and 8.00 cm? (d) At very large positive or negative values of x, the electric field approaches zero in both (a) and (b). In which does it most rapidly approach zero and why? (e) At what position to the light of 11.0 cm is the total electric field zero, other than at infinity? (Hint: A graphing calculator can yield considerable insight in this problem.)